Flash-ignitable energetic material

ABSTRACT

Carbon nanotubes and activated carbon containing a metal such as palladium release a photoacoustic effect when subjected to a flash of light. A light ignitable, energetic composition is produced by mixing one of them with an energetic material such as carbon black powder or ammonium perchlorate.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to a light ignitable, energetic materials.More specifically, the invention relates to light ignitable, energeticmaterials containing carbon nanotubes or activated carbon containing ametal.

[0003] 2. Discussion of the Prior Art

[0004] A carbon nanotube (CNT) is a hollow nanostructure consistingessentially of a graphitic plane rolled into a thin tube, both ends ofwhich can be closed by a fullerene-type dome structure. The existence ofCNT's was originally discovered by S. Iijima [see Nature 354, 56(1991)]. The material exhibits various interesting mechanical andelectrical properties. There exists two forms of carbon nanotubes,namely single walled nanotubes (SWNT) and multiwalled nanotubes (MWNT).

[0005] It has recently been reported by P. M. Ajayan et al in Science,Vol. 296, 705 (2002) that carbon nanotubes release a large photoacousticeffect when sujected to a flash of light caused by the absorption of thelight. It seems that the phenomenon is predominantly present in SWNT'sand that the temperature of the process can reach 1500° C. The inventorshave also determined that activated carbon containing a metal such aspalladium also possesses the property of releasing a photoacousticeffect when subjected to a flash of light.

GENERAL DESCRIPTION OF THE INVENTION

[0006] The object of the present invention is to exploit the abovedescribed property of carbon nanotubes and activated carbon containing ametal to produce a light ignitable, energetic material.

[0007] Accordingly, the present invention relates to a light ignitable,energetic composition comprising an intimate mixture of an energeticmaterial and one of carbon nanotubes and activated carbon containing ametal selected from the group consisting of palladium, iron, nickel,cobalt, aluminum, copper, zinc, potassium, sodium and titanium.

[0008] The invention also relates to a method of preparing a lightignitable, energetic composition comprising intimately mixing anenergetic material and one of carbon nanotubes and activated carboncontaining a metal selected from the group consisting of palladium,iron, nickel, cobalt, aluminum, copper, zinc, potassium, sodium andtitanium.

[0009] A variety of energetic materials can be used in the method of thepresent invention. Such energetic materials include carbon black powder,ammonium perchlorate (AP), hexogen (RDX), octogen (HMX), pentaerythritoltetranitrate, (PETN), trinitrotoluene (TNT), nitroglycerine,nitrocellulose, ammonium nitrate, lead azide, lead styphnate, nitroplasticizers and picric acid. While the carbon nanotubes can be SWNT orMWNT, the single walled nanotubes are preferred.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0010] In general terms, the invention takes advantage of thephotoacoustic effect of carbon nanotubes when subjected to a burst oflight, e.g. a camera flash to ignite an energetic material. In order totest the theory, different carbon nanotubes were used, the most commonone being a SWNT commercial available from Carbon Nanotechnologies,Inc., Houston, Tex. Different percentages of carbon nanotubes (1-90weight percent) were manually mixed (gently) with carbon black powder.Initially, the most efficient composition contained 5 weight percentSWNT mixed with 95 weight percent Grade 7 carbon black powder. Thecomposition exploded instantaneously after being subjected to a cameraflash. It was found that carbon black powder with the smallest particlesize was the most effective. The same effect was observed when activatedcarbon containing a metal, e.g. palladium was mixed with carbon blackpowder, and the resulting mixture was exposed to a camera flash.

[0011] The invention will be better understood from the followingexamples.

EXAMPLE 1

[0012] 3 weight percent of crude carbon nanotubes were mixed with 97weight percent ground ammonium perchlorate. The mixture was homogenizedusing ball milling equipment for 15 minutes. The balls used in the millwere made of glass. The resulting composition was then exposed to anintense flash using a commercially available Vivitar (trademark) flash.The power of the flash was 200W/cm² at a distance of 4.5 cm.

EXAMPLE 2

[0013] The procedure of Example 1 was repeated using 3%, 5%, 10% and 20%carbon nanotubes. At a concentration in excess of 20% nanotubes, theignition phenomenon was less efficient, i.e. the combustion process(explosion) appears to be incomplete.

EXAMPLE 3

[0014] Energetic formulations containing carbon nanotubes and RDX, TNT,black powder or AP were ignited at distances from 3 to 7 cm using theVivitar flash. In a few cases, ignition was possible from a distance asgreat as 14 cm.

EXAMPLE 4

[0015] The method of Example 1 was repeated using 5 weight percentactivated carbon containing palladium (97% carbon and 3% palladium) with95 weight percent ground ammonium perchlorate. The mixture washomogenized using the same ball milling equipment as in Example 1. Thecomposition was ignited using a flash; however, the process was lessefficient than when using carbon nanotubes.

EXAMPLE 5

[0016] The ignition effect was observed for a variety of mixtures ofactivated carbon containing 3-30% palladium catalyst and a variety ofenergetic materials. The ignition effect was similar to that observedwhen using carbon nanotubes, but seemed to be less efficient after 3 to5 days. It is believed that the activated carbon was absorbing waterwhich reduced the efficiency of the ignition phenomenon.

[0017] Compositions in accordance with the present invention can be usedfor light ignited pyrotechnic effects and as light ignited triggers fordetonators, gas generators and air bags.

[0018] Various modifications may be made to the described embodimentswithout departing from the spirit and scope of the invention as definedin the appended claims.

1. A light ignitable, energetic composition comprising an intimatemixture of an energetic material and one of carbon nanotubes andactivated carbon containing a metal selected from the group consistingof palladium, iron, nickel, cobalt, aluminum, copper, zinc, potassium,sodium and titanium.
 2. The composition of claim 1, wherein theenergetic material is selected from the group consisting of carbon blackpowder, ammonium perchlorate, hexogen, octogen, pentaerythritoltetranitrate, trinitrotolune, nitroglycerine, nitrocellulose, ammoniumnitrate, lead azide, lead styphnate, nitro plasticizers and picric acid.3. The composition of claim 2, wherein the mixture contains an energeticmaterial and single walled carbon nanotubes.
 4. The composition of claim3, wherein the mixture contains 1 to 20 weight percent carbon nanotubes,the remainder being the energetic material.
 5. The composition of claim3, wherein the mixture contains 95 weight percent of the energeticmaterial and 5 weight percent carbon nanotubes.
 6. The composition ofclaim 4, wherein the mixture contains 95 weight percent carbon blackpowder and 5 weight percent carbon nanotubes.
 7. The composition ofclaim 3, wherein the energetic material is ammonium perchlorate.
 8. Thecomposition of claim 7, wherein the mixture contains 97 weight percentammonium perchlorate and 3 weight percent carbon nanotubes.
 9. Thecomposition of claim 7, wherein the mixture contains 95 weight percentof ground ammonium perchlorate and 5 weight percent of activated carboncontaining 97 weight percent carbon and 3 weight percent palladium. 10.A method of preparing a light ignitable, energetic compositioncomprising intimately mixing an energetic material and one of carbonnanotubes and activated carbon containing a metal selected from thegroup consisting of palladium, iron nickel, cobalt, aluminum, copper,zinc, potassium, sodium and titanium.
 11. The method of claim 10,wherein the energetic material is selected from the group consisting ofcarbon black powder, ammonium perchlorate, hexogen, octogen,pentaerythritol tetranitrate, trinitrotolune, nitroglycerine,nitrocellulose, ammonium nitrate, lead azide, lead styphnate, nitroplasticizers and picric acid.
 12. The method of claim 11, wherein singlewalled carbon nanotubes are mixed with the energetic material.
 13. Themethod of claim 12, wherein the energetic material is ammoniumperchlorate.
 14. The method of claim 12, wherein the energetic materialis carbon black powder.
 15. The method of claim 11, wherein groundammonium perchlorate is mixed with activated carbon containingpalladium.